The long-term objective is to describe quantitatively the changes that occur in the response properties of central gustatory neurons as amino acid taste information is relayed from peripheral nerves through to brainstem and forebrain taste nuclei. The specific aims are to determine the response properties of single peripheral, medullary and pontine taste neurons and to determine the nature and extent of interaction between taste and tactile input at the different synaptic levels of organization. Extracellular, electrophysiological unit recordings will determine whether different "types" of amino acid responsive taste fibers exist and whether their response properties are modified in the brainstem. An estimation of the relative extent of bimodality (taste and tactile responsiveness) at each synaptic level will be determined. In addition, possible convergence between "odor" (olfactory and/or nasal trigeminal) and taste pathways will be investigated. Also, a study of the response properties of the recently identified telencephalic taste area of the catfish will be initiated to provide initial information on forebrain processing of amino acid taste information. Statistical analyses of the response data, histological marking of recording sites and neuronal tracing studies with horseradish peroxidase (HRP) will all provide useful information for an accurate interpretation of the experimental results.